Breathable gas regulating apparatus



ct. 14, 1958 R. KIMES ETAL A 2,855,923

BREATHABLE GAS REGULATING APPARATUS Filed Sept. 8, 1953 3 Sheets-Sheet 1IO w 0's 2 RUBERT muss, ROBERT L. KESLER,

STANLE'YJ. MITCHELL,

INVENTORS.

x BY 4 Oct. 14, 1958 R. K!MES ETAL BREATHABLE GAS REGULATING APPARATUS 3Sheets-Sheet 5 Filed Sept. 8, 1953 F/ga.

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I400 I200 I000 800 600 400 200 SUPPLY PRESSURE ROBERT K/MES ROBERT L.KELER, STANLEY .1. MITCHELL,

- INVENTORS.

United States Patent 2,855,923 BREATHABLE GAS REGULATING Ai PARATU'sRobert Kimes, Culver City, Robert L. Kesler, Pacific Palisades, andStanley J. Mitchell, Los Angeles, Calif., assignors to The GarrettCorporation, Los Angeles, Calif., a corporation of CaliforniaApplication September 8, 1953', Serial No. 378,856

21 Claims. (Cl. 128142) The present invention relates generally tobreathing apparatus and relates more specifically to apparatus enablingthe user to breathe both above and beneath the surface of water, inpoisonous atmospheres, at high altitudes, suitable for use in emergencyresuscitation.

Heretofore, breathing apparatuses designed for use in situations similarto those for which the present device is to be used have had inherentinadequacies such as, for example, uncomfortable or prohibitiveresistance to breathing, a steady increase in such resistance as thebreathable gas supply was exhausted, dangerous conditions resulting fromapparatus failure and failure to provide sufiicient warning to the userof the approach of exhaustion of the breathable gas supply.Additionally, prior devices have often been extremely heavy, cumbersomeand difiicult to maintain in operating condition and adjust for optimumperformance. Furthermore, a considerable amount of re-breathing ofexhalation products has occurred in prior devices of this character,such re-breathing being often harmful from a physiological standpoint.

Accordingly, it is an important object of the present invention toprovide breathing apparatus which will overcome the beforementionedditficulties experienced in connection with prior breathing devices.

It is another important object of the present invention to provide aunitary, light weight, reliable, and efficient breathing apparatuswherein the breathing resistance is maintained at a substantiallyconstant, low level throughout the entire useful period during whichcompressed breathable gas of varying pressure is utilized.

A further object of the present invention is to provide a breathingapparatus of the type described, wherein sub-. stantially n mixing offresh breathable gas with exhalation products occurs.

A still further object of the present invention is to provide abreathing apparatus wherein means are provided to interrupt the flow ofbreathable gas from a source when the gas source approaches exhaustion,thereby to warn the user of the limited gas supply still available andto permit manual operation of a suitable valve for admitting the balanceof the breathable gas to the breathing apparatus, thus providing anadditional period of use during which time the user may seek abreathable ambient atmosphere.

It is another object of the present invention to provide a check valvearrangement for conducting exhalation products to ambient atmosphere,means being provided to prevent inadvertent reverse gas flow due tosurging of the ambient medium, such as liquid or the like, and forpreventing admission of such ambient medium to the respiration system ofthe user.

Other and further important objects of the present invention will becomeapparent from the disclosures in the following detailed description,appended claims and accompanying drawings, wherein:

2,855,923 Patented Oct. 14, 1958 ice Fig: 1 is a transverse sectionalview of the breathing apparatus of the present invention;

Fig. 2 is an enlarged fragmentary sectional view showing the regulatingmechanism in the position assumed during inhalation;

Fig. 3 is a sectional View showing portions of the gas reserve valve andtaken substantially as indicated on line 33 Fig. 2; p

Fig. 4 is a fragmentary sectional view showing portions of the presentregulating mechanism in the position assumed during exhalation;

Fig. 5 is a top plan view of the present apparatus with portions cutaway;

Fig. 6 is a graph illustrating the breathing resistance encountered inprior breathing devices; and

Fig. 7 is a graph similar to Fig. 6 showing the breathing resistance ofthe present breathing apparatus.

Referring primarily to Fig. 1 of the drawings, the breathing apparatusof the present invention is shown as indicated generally at 10. Ingeneral, the apparatus includes a regulator 11 that is attached by anysuitable means to a source of breathable gas such as, for example,

a tank 12. The regulator 11 is connected, by means of a flexiblenon-collapsing inhalation conduit 13 and a similar exhalation conduit14, to a suitable mouthpiece indicated generally at 15. The conduits 13and 14 have sufiicient length so that they may extend preferably aboutthe shoulders of the user to insure freedom of movement without undueslack that would permit their becoming fouled in objects or structurespassed by the wearer.

The regulator 11 includes a unitary body portion 16 that is providedwith a first chamber 17 for receiving a breathable gas and a secondchamber 18 for receiving exhalation products. The chamber 17communicates with the inhalation conduit 13 by means of a passage 19formed laterally in one side of the body 16, the outer end of which isformed with a boss 20 to which the conduit 13 is secured by means of aclamp 21. .The chamber 18 communicates with the conduit 14 by means of apassage 22 that is formed laterally in the other side of the body 16 andterminates Within a boss 23, the conduit 14 being secured thereto bymeans of a clamp 24. A partition 25 is positioned in a recess 26 formedin the bottom of the chamber 18 and is secured to the body portion 16 bymeans of a plurality of screws 27. The partition 25 thus separates andforms adjacent sides for the chambers 17 and 18.

The body 16 of the regulator includes a downwardly extending portion 28(see also Fig. 2) that extends from the portion of the body forming thechamber 17. A nipple 29 is threadably disposed, as at 30, in the portion28, and has an axial bore 31. The nipple 29 is secured to a fitting 32of a supply tank shut-off valve 33'by means of a nut 34. A filter 35 maybe positioned in the bore 31. Breathable gas from the tank 12 isconducted through the valve 33, filter 35 and bore 31 to a recess 36 inthe portion 28. p i

A restricting passage 37 is formed radially outwardly from the recess36, the outer end of this passage being provided with a conical seat 38against which a closure member 39, of a gas reserve valve, indicatedgenerally at 40, is adapted to rest. The closure member 39 is generallytriangular in cross-section (see Fig. 2) and is slidably disposed in alaterally extending cylindrical bore 41 formed in a projection 42 fromthe portion 28 of the body 16.

A,fitting 43, having an internal recess 44 that is of substantiallythe-same diameter as the bore 41, is threadablydisposed in the outer endof the projection 42. The fitting 431s adapted to rotatably and slidablysupport a shaft 45, the inner end of which is, provided with aueIL-larged disc 46, there being a packing gland 47 disposed in the inner endof the bore 44 and about the shaft 45. The outer end of the fitting 4.3.h s a cam surface 48,- that is adapted to co-operate with a cam.follower 49, formed: on a lever 50, the shaft 55 extending throughthelever and being sec red ther o. by m ans. 01.5 a nut: 5.1- The disc 46is provided with a peripheral; grgovgfil, Fig. 3 t a ap ed eo-ene etewith a. stop. ab .53. h ext nds ewer t ies; rom he fitt 4 o a toleek theshaft in its axial position at each end of. the travel ofthe lever 5Qand provides a stop means to limit rotation f the r: Thu an f eet at essre etir e r thev disc 46 is eliminated. y

Pa r f. eerhs ssi h a -ins 5 and re d p respectively between theenlarged; disc; 46 of. the shaft 5 en th eles tre mehs erh. and etwee aPQr ier f 'p k n lahttfl eat! he dire. 4. A eri ar ie push, re 6 eeeeeure t 9 the s er end oi h lev 5031's by e ht he 5.7 the-eens r et eei: theses reserve valve being such that upon rotation of the lever 50 yh ard he e rh et feee 49 wi l e ete. against the cam surface 4.8 therebyto withdraw the shaft 45,, thus compressing the spring 55 and relievingthe mp e v r e t' he s ing 5 h a o in or PUIP t e rei a e ere f y de cedacume- 4 to. be. received in the seat of the bore 68. the conicalsurface of the portion 71 co-gperating with the matching conical surfaceon the valve seat 69. When the valve 70 is seated, as shown in Figs. 1and 4, the extension 72 extends into the end of the bore 68 adjacent theconical seat 69. The construction of the operating end of the al emember is such that a posi iv occlusion of the F1 passage 68 isprovided. When the valve member 70 is Under normal conditions, theclosure member 39 i s maintained in a closed position, with respect tothe outerend of the. restricted passage 37, by action of the com-,pression spring 54. The. force of the breathable gas e h he lo re err ret r: a ides hereof h h el need he e s i h eere r r o Pr s sure actingupon. the relatively small area of the end of the portion 38 when themember is closed. The forceoi h in s e f eieht n rma t re me th for athe. see e t i en he t of e Po n. 3 U de e eihee td t e o. he. e in e eu ly iscuss d. the Pre re. f nt a s in e ee e su e member- 3 wi e 1 h sto. e t e e er en l y hea ie f ee e rt f t Por i n. er i n rmally Pre enh s to re m th er e h r n 54. causing compression thereof and opening ofthe closure phragm 82 is provided with upper and lower bac ingmemb r- Pit e; e Q e h h he. r

e e Pe ra 1 eas hte he rmler hd r; e h r 41, as shown in Big. 2.

An angularly disposed passage 5 8 is adapted to. con; tthe h a h b e. ererh. h irmer end'e the r 41 to the inner end of a recess 59 formedaxially in the body portion 28 adjacent the chamber 17. A. reduced e ere e 60. xte ds ew wer l om he hettom of the recess 59.

A. he a em nt, 6 as l i ri et r et s. 61a th t e s de spo ed. i h eee'send, 6 respectively A p ir f sea in n s 6. .er 65 a e di p oscd about theportions 6 2 and 6 3: try-provide a seal be; tween the element 61 andthe body portion 16 The axial length of the portion 62 is slightlyshorter than the axial depth of the recess 59, so as to present anannular shoulder 66 that defines a pressure differential area that ma beaeted p n y he P ssure. f hehr athe le ga being admitted to the innerend of the recess 59'. The element 6 1 is provided with a lateral bore67 that commhnieetee t e ne nd of he re ees. .2 and with.v an axial bore68 through the element 61 theouter end of the bore 68 being providedwith a conical valveseat 69; that is adapted to co-operate with ametering valve mem; ber 70 The valve seat 69 together with the elernent61 t e relative to e hedy efj h ppa a us. and. may termed e me n va ve.-ett r h Purueeee description.

The metering valve member 70 has a conical tip, or operating end"portion 71 that may be made from Nylon, or the like, for example, thisportion being formed with a cylindrical extension 72/ at theaperithereof, the portion 71 and extension 72 being adapted elesed', the presu infer ntial: rea or hic the see within the passage 53 is, acting ismain ained at a constant value due to the protrusion of the extension 72into the bore 68. It may be seen that as the valve member 70 is m d i emi sea 62, he xtension 72 m st fi s clear the outer end of the bore 68,thus presenting a large aperture for the flow of the breathable gas fromthe bore 68. The relatively large contact area between the portion 71and the valve seat 69 further greatly reduces cold flowand/or we r of thmaterial of, the p r i n 71 and su s on r. tro bler e operating i o he.unit.

e h nk o h lv mem er 70. ex n p a l through an ax a ly ispo ope in 3 ithe parti i 2.5 and n th ham A p on p n 74 is disposed about the shankof the valve member 70 be; tween the partition 25 and the head portionof the. valve member, thereby to urge the valve member toward the. valveseat 69. A second compression spring 75, having a, greater force thanthat or the spring 74, is dosposedj between the partition 25 and aflange 76 formed on the element 61, this second compression springacting to op- Pos he force o he b ea a a acting p n he ar 66 in a mannerandfor a purpose to be hereinafter more te ly desc ibed- A. respirationpressure responsive flexible diaphragm 82' provides a movable wallforone side of the chamber 18 t s aphragm b amp d, t e e y p t o 16. anda protective cap 83 by screws 84, Fig. 5. The diaplates 85 and 86 thatare secured to each other and to the diaphragm by rivets 87, An enlargedopening- 88 is. provided through the central area of the diaphragm 82and backing plates 85 and 86 for reception of a bushing 89,. The bushing89 may be of semi-flexible material such as rubber, for example, andprovided with a. cylin-. drical portion 90 that is adapted to bereceived in the opening 88, there being an annular flange 91 extendingover the backing plate 86 adjacent theperiphery of the opening 88. Thebushing 89 has an enlarged annularportion 92 that is adapted to extendoverthe-surface of the backing plate 85. An axially extending annularflange 93 is' formed on the periphery ofthe portion 92, this flangehaving outwardly projecting tabs 94. Theouter surface 95 of the bushing89 has a conical configuration against which a normally closed disccheck valve. member 96 is adapted to normally lie. The check valvemember 96 is provided with a central stem 97 that has an enlargement 98.The stem 97 projects through a central opening 99 in the bushing 89, theportion 98 being received in an enlarged recess 1 00 in the inner sideof the bushing 89. The bushing 89 is further provided with a pluralityof axially extending fluid flow passages 101 to provide means forventing exhalation products from the chamber 18 to ambient atmosphere orthe surrounding fluid medium. These exhalation products escape throughthe; passages 101,, past the check valve member 9.6 and ou hr e r 83.bywa of pe gs. .0. nd g through thecap 83.

It may be seen that the fla ge 93, formed in the bush; ing 89 andsurrounding the flexible checlr valve member- 96, serves to prevent thepossible wash or surge of the ambient fluid, medium, from unseating thisvalve' nember and flowing into the chamber 18. The periphery of thevalve member 96'is thus protected against being lifted in a mannertending to reverse its position, orgca use malfunction thereof. a

The check valve member 96 may be made from any suitable flexiblematerial such as rubber, for example. Upon outward movement of thediaphragm 82 away from the chamber 18, the valve member 96, togetherwith bushing 89, is carried outwardly, the tabs 94 limiting outwardmovement of the bushing and diaphragm by ultimate contact with the innersurface 103 of the cap 83. It may be seen that the bushing 89, togetherwith the flexible check valve member 96, eflfectively forms a unitarystructure, the inner end portion of the stem 97 being. pulled throughthe bore 99 during assembly by means of an elongated portion (not shown)that is formed on the inner end of the stem 97 and subsequently removedafter assembly. The bushing 89 merely snaps into place in the opening88. In order to alleviate any possibility of the check valve member 96adhering to the inner surface 103 of the cap 83, a plurality of radiallyextending ribs 104 are formed outwardly from a central boss 105 in the-cap. These ribs thus interrupt an otherwise smooth surface of the cap.

The stem portion of the metering valve member 70 is provided with anenlargement formed by a washer 106 that is retained in place on the endof the stem by a suitable snap ring 107, for example. An annular ring108 is formed outwardly toward the chamber 18 from the partition 25 andspaced radially from the valve member 70. This annular ring is providedwith peripheral notches 109 that are adapted to receive levers 110, theinner ends of which are bent as at 111. The ends of the bent portions111 are adapted to engage a radially inwardly directed surface of theportion 108 to retain the levers in place. The levers 110 are adapted toextend from the valve member stem, beneath the washer 106 and outwardlythrough the notches 109 to normally engage the diaphragm plate 86 as at112, the engagement ends of the levers 110 being suitably rounded inorder to reduce friction between these levers and the plate. It may beseen that when the diaphragm 82 moves inwardly toward the chamber 18,the levers 110 will be depressed, thus rocking these levers about thering portion 108 and lifting the valve member 70 from its normalposition on the seat 69. The comparative lengths of the levers 110between the notches 109 and the engagement point 112 with the diaphragmplate 108, and between the notches 109 and the point of contact with thewasher 106, is such as to provide a large mechanical advantage forlifting the valve member 70 from the seat 69.

The mouthpiece 15 has a transverse section 114 that is provided with apassage 115 therethrough. The inhalation and exhalation conduits 13 and14 are secured to the portion 114 by suitable clamps 116. A laterallyextending portion 117 is formed outwardly from the transverse portion ofthe mouthpiece and has a passage 118 therethrough that communicates withthe passage 115. A flexible member 119 is attached to the outer end ofthe portion 117, this flexible member having an elongated laterallyextending flange 120 that is adapted to be inserted beneath the lips ofa user, there being bit portions 121 that are inserted between the teethof the user so as to retain this mouthpiece in place. The user of theapparatus must breathe through his mouth when utilizing the presentdevice, the eyes and nose generally being covered by a suitable faceplate or mask. In this connection it is to be understood that the devicemay be used with a suitable mask having an integral mouthpiece or with amask wherein the breathable gas is delivered in such a manner as topermit breathing through either the nose or mouth.

During operation and use of the present breathing apparatus, in, forexample, situations requiring submersion in a liquid, it is customarythat the device be secured to the back or" the user, with the regulator11 disposed substantially at the level of the lungs of the user. Whenplaced in this manner, the surrounding fluid medium will exert on thediaphragm 82 and on the lungs of the user substantially the samepressure even though the user may assume various attitudes. L

The conduits 13 and 14 are adapted to extend over the shoulders of theindividual and the mouthpiecelS is retained in the mouth as hereinbeforedescribed. The breathable gas in the tank 12 may initially be compressedto a pressure of 2000 p. s. i., for example, and the breath-' previouslydescribed, the device provides a flow path or restricted passage for thebreathable gas from the source to a point of use, this passage beingdefined by the 'bore' 31, recess 36, bores 37 and 41, passage 58, andbores 67 and 68 to the chamber 17, and from the chamber 17 by way of thepassage 19 and inhalation conduit 13 to the mouthpiece 15. Assuming thatthe initial pressure of the gas supply is 2000 p. s. i., a pressure dropis experienced across the closure member 39 so that the gas existing atthe inner end of the bore 41 will be at approximately 1700 p. s. i. Thegas at this reduced pressure is transmitted through the passage 58 andinto the inner end of the recess 59, thereafter to act upon the area 66of the element 61, thereby to move the element 61 against thecompression of the spring 75 to the position shown in Fig. 1. Inwardmovement of this element is limited by a plurality of downwardlyextending fingers 126 from.

the partition 25 and spaced radially from the valve member 70, thesefingers being adapted for engagement with the flange 76 on the element61.

Upon inhalation, a reduction in the pressure existing in the conduits 13and 14 as well as in the chambers 17 and 18 is created, thus causing thediaphragm 82 to be moved inwardly toward the chamber 18 to depress thelevers and lift the valve member 70 from the seat 69 as illustrated inFig. 2. As inhalation is started and as the valve member 70 is liftedfrom the seat 69, a differential in pressure is created across theclosure member 39, thereby, as hereinbefore described, causing theclosure member 39 to move in a direction to compress the spring 54 andpermit flow from the bore 37 through the bore 41 and into the passage58. Opening and closing of the closure member 39 occurs therefore witheach inhalation and exhalation cycle. Thereafter a metered amount of thebreathable gas is admitted to the chamber 17 and con: duit 13 by way ofrestricted passages defined by the bores 67 and 68. It may be seen thatthe diaphragm 82 is exposed on one side to the pressure in the chamber18, this pressure being substantially the same pressure as existing inthe lungs of the user, and on the other side to the pressure of thesurrounding fluid medium, thereby to maintain a pressure in the lungswhich substantially equals that of the surrounding fluid medium, thuspreventing possible damage to the lungs from diflerential pressures thatmight otherwise exist. At the end of each inhalation, the diaphragm willreturn to a neutral position, as shown in Fig. l, to permit the valvemember 70 and closure member 39 to close.

Upon exhalation, exhalation products are conducted through the passages118 and in the mouthpiece 15, into the exhalation conduit 14 and chamber18, whereupon a differential in pressure is created across the diaphragm82 to cause this diaphragm to move outwardly until the tabs 94 engagethe inner surface 103 of the cap 83, the diaphragm assuming the positionindicated in Fig. 4. Exhalation gases will now flow through the passages101, past the periphery of the flexible valve member 96, into theinterior of the cap 83 and out through the openings 102 to ambientatmosphere or the surrounding fluid medium. It is to be noted thatsubstantially no mixing of the breathable gas with the exhalationproducts is encountered, with the exception of the gas existing in thevery small area of the passage 115 in the mouthpiece 15, thus reducingthe amount of carbon dioxide present in the inhaled gas to an absoluteminimum and alleviating the adverse physiological effects that mayaccompany re-breathing of exhalation products.

In prior devices designed to accomplish a purpose similar to that of thepresent invention, as the available pressure of the breathable gas wasreduced through consumption thereof, it often became increasinglydifficult for the user to breathe because of the force of gas pressureacting on the metering valve decreasing with respect to thesubstantially constant spring force urging the valve member towardclosed position. In other devices, breathing resistance has been veryhigh when the gas supply pressure was high and was reduced slightly asthe supply pressure was reduced. Such devices are very unsatisfactory asconsider-able fatigue is experienced by the user in an effort toovercome high breathing resistance. This undesirable condition iscorrected in the present apparatus, the force of the decreasing pressureof the breathable gas upon the pressure differential area 66 beingcorrespondingly reduced in opposition to the force of compression spring75. Hence, the element 61 is permitted to float or move toward aposition approximating that shown in Fig. 2, movement of the element 61carrying the valve seat 69, in a floating manner, farther away from thepartition 25, thus relaxing the spring 74 and reducing the force thereoftending to seat the valve member 70 on the valve seat 69. Movement ofthe element 61'is such that the force of the spring 74 is maintainedslightly higher than the force exerted by the compressed breathable gasupon the extension 72 of the valve member, thus maintaining uniformbreathing resistance. This substantially constant resistance tobreathing is shown clearly in Fig. 7 by the curve '1'30,'the breathingresistance being maintained well below a desirable value of 2.7 inchesof water maximum differential pressure, and at a substantially constantlevel throughout the entire pressure range of the gas contained in thetank 12 from 2000 p. s. i. to approximately 550 p. s. i., this lowerpressure existing when the element 61 engages the bottom of the chamber17. This condition is contrary to the situation existing in priordevices, wherein such low maximum breathing resistance has either notbeen maintained or the breathing resistance increased rapidly throughoutthe entire period of use of the air in the supply tank. In Fig. 6, acurve 131 represents the situation existing in prior devices.

As the'pressure of the breathable gas is reduced to 300 p. s. i., forexample, and as the supply approaches exhaustion, the pressuredifferential across the closure member 39 is gradually reduced untilthis difierential is insufficient to overcome the force of the spring 54in closing the closure member 39, whereupon the flow of breathable gasto the reces 41 will be shut off, thus providing-a warning to the userthat the supply of gas is approaching exhaustion. Immediately, thelanyard 56 may be pulled to rotate the lever 50 .to the position shownin Fig. 2, thusmoving the shaft 45 outwardly by action of the camsurface 48 and cam follower 49, and relaxing the spring 54. This actionreduces the force of the spring 54 and permits the closure member 39 tobe unseated by the succeeding inhalation cycle. Thereafter, the closuremember 39 remains open to 'enable free flow of 'gas to the passage '58.After such movement of the lever 50, and depending upon the physicalcondition of the user and the volume of 'the tank 12, five to-eightminutes supply of breathable gas then remains, permitting the user tosurface or to seek a breathable ambient atmosphere.

It may thus be seen that the present device adequately fulfills theobjects set vouthereinbefore and provides a "mechanism thatmay be usedin a variety of situations eitherunder water or 'wherever unbreathable,eontaminated or poisonous atmospheres are encountered. In all'conditionsof use, the device of the present invention is completely fail-safe in.that breakage or malfunction of .importantparts would notresult indanger to the user. 'For example, if either of the springs 54 or 55 inthe gas reserve valve should break, a free flow of gas would merely bedelivered to the passage 58, and into the balance of the unit, somewarning of the exhaustion of breathable gas thereafter being provided byincreased breathing resistance near the point of gas exhaustion. If thecompression spring 75 should fail, the force of the breathable gasacting upon the pressure differential area 66 would merely move theelement 61 until the fingers 126 engage the flange 76, thus causing anincrease in breathing resistance, this resistance still being acceptablylow, as indicated by the curve 132 in Fig. 7, and breathing can beeasily maintained. It the metering valve spring 74 should fail, a freeflow of gas would be permitted to the chamber 17 until the pressure inthe supply tank 12 dropped to a level that would be balanced by thereduced force of the broken spring 74 thus permitting the metering pinto resume its operation. In this condition. the excess gas flowing intothe chamber 17 would be conducted through the inhalation conduit 13,through the passage in the mouthpiece 15 and through the exhalationconduit 14, into the chamber 18 thereafter to flow into the surroundingfluid medium through the check valve 96. If such a condition shouldexist, approximately 15 minutes of uninterrupted breathing would stillbe available.

It is to be noted that the present device may be readily and easilyserviced and may be maintained in proper working order without a greatknowledge of such devices. There are no critical adjustments necessaryfor any of the components of the device and no calibration of portionsor elements thereof is required. Additionally, the simple and ruggeddesign of the present device will insure a considerably longer servicelife than that provided by prior similar units, there being relativelyfew parts that will wear, such possible wear being virtually eliminatedby the present arrangement. Various components of the device may bereplaced by the average individual without the necessity for returningtheunit to the manufacturer.

We claim:

1. A breathable gas regulating device comprising: first passage meansfor conducting a breathable gas from a source to a point of use;achamber in said device; second passage means for conducting expired gasfrom said point .of use to said chamber; a check valve for controllingfluid fiow from said chamber to the surrounding fluid; a movable wallforming one side of said chamber, said movable wall'being subjected onone side to the pressure in said chamber and onthe other side to thepres sure of the surrounding fluid; valve means for controlling the flowof breathable gas through said first passage means; means for biasingsaid valve means toward a closed position; means operably associatedwith said movable wall'for opening said valve means upon a reduction ofthe pressure in said second passage means and in said chamber thereby topermit flow of said breathable gas through said first passage means; andmeans operably associated with said valve means for substantiallymaintaining constant the force biasing said valve means toward a closedposition and consequently the force required to open said valve means asthe pressure of said breathable gas is reduced-through use thereof.

'2. A breathable gas regulating device comprising: first passage meansfor conducting a breathable gas from a source to a point of use; achamber in said device; second passage means for conducting expired gasfrom said point of use to said chamber; a movable wall forming one sideof said chamber, said movable wall being subjected on oneside to thepressure in said chamber and on the other side to the pressure of thesurrounding fluid medium;-valve means for controlling the flow ofbreathable gas through said-first passage means; means for biasing saidvalve 'means toward-a closed position; means operably associated withsaid'movable wall for opening: said valve means upon a reduction of thepressure in said second passage means and in said chamber thereby topermit flow of said breathable gas through said first passage means; andmeans responsive to a reduction in pressure of said breathable gas fromsaid source to maintain at substantially a constant level the forcebiasing said valve means toward a closed position and consequently themagnitude of said reduction in pressure in said second passage means andin said chamber necessary to move said movable wall and open said valvemeans.

3. A breathable gas regulating device comprising: first passage meansfor conducting a breathable gas from a source to a point of use; achamber in said device; second passage means for conducting expired gasfrom said point of use to said chamber; a movable wall forming one sideof said chamber, said movable wall being subjected on one side to thepressure in said chamber and on the other side to the pressure of thesurrounding fluid medium; a check valve for controlling the flow of gasfrom said chamber, said check valve being carried by said movable wall;valve means for controlling the flow of breathable gas through saidfirst passage means; means for biasing said valve means toward a closedposition;

means operably associated with said movable wall for opening said valvemeans upon a reduction of the pressure in said second passage means andin said chamber thereby to permit flow of said breathable gas throughsaid first passage means; and means responsive to a reduction inpressure of said breathable gas at said source to maintain atsubstantially a constant level the force biasing said valve means towarda closed position and consequently the magnitude of said reduction inpressure in said second passage means and in said chamber necessary tomove said movable wall and open said valve means.

4. In a breathable gas regulating device: a regulator; a first chamberin said regulator for receiving a breathable gas from a source; valvemeans for controlling the flow of said gas into said first chamber;means resiliently urging said valve means toward a closed position;inhalation conduit means for conducting breathable gas from said firstchamber to a point of use; a second chamber in said regulator;exhalation conduit means for conducting exhalation products from saidpoint of use to said second chamber; a movable wall having one sideexposed to the pressure in said second chamber, the other side of saidWall being exposed to the pressure of the surrounding fluid medium; acheck valve for controlling fluid flow from said second chamber; meansoperably interconnecting said movable wall and said valve means,whereby, upon inhalation, a reduction in pressure is created in saidexhalation conduit means and in said second chamber thereby to move saidmovable wall and open said valve means to permit a flow of breathablegas into said first chamber and into said inhalation conduit means andmeans responsive to variations in pressure of the gas at the source tovary the effective force of the valve closing means, such effectiveforce being varied in a predetermined manner relative to the variationsin the gas pressure at the source.

5. In a breathable gas regulating device: a regulator; a first chamberin said regulator for receiving a breathable gas from a source; valvemeans for controlling the flow of said gas into said first chamber;means resiliently urging said valve means toward a closed position;inhalation conduit means for conducting breathable gas from said firstchamber to a point of use; a second chamber in said regulator;exhalation conduit means for conducting exhalation products from saidpoint of use to said second chamber; a movable Wall having one sideexposed to the pressure in said second chamber, the other side of saidwall being exposed to the pressure of the surrounding fluid medium; acheck valve for controlling fluid flow from said second chamber, saidcheck valve being carried by said movable Wall; means operablyinterconnecting said movable wall and said valve'mean's, whereby, uponinhalation, a reduction in pressure is created in said exhalationconduit means and in said second chamber thereby to move said movablewall and open said valve means to permit a flow of breathable gas intosaid first chamber and into said inhalation conduit means and meansresponsive to variations in pressure of the gas at the source to shiftthe closing point of said valve means and thus vary the effective forceof said valve closing means.

6. In a breathable gas regulating device: a regulator; a

first chamber in said regulator for receiving a breathable gas from asource; valve means for controlling the flow of said gas into said firstchamber; a floating valve seat associated with said valve means;inhalation conduit means for conducting breathable gas from said firstchamber to a point of use; a second chamber in said regulator;exhalation conduit means for conducting exhala tion products from saidpoint of use to said second chamber; a movable wall having one sideexposed to the pressure in said second chamber, the other side of saidwall being exposed to the pressure of the surrounding fluid medium; acheck valve for controlling fluid flow from said second chamber; andlever means operably interconnecting said movable Wall and said valvemeans, whereby, upon inhalation, a reduction in pressure is created insaid exhalation conduit means and in said second chamber thereby to movesaid movable wall inwardly toward said second chamber and open saidvalve means to permit a flow of breathable gas into said first chamberand into said inhalation conduit means. 7 V

7. In abreathable gas regulating device: a regulator;

a first chamber in said regulator for receiving a breatha ble gas from asource; valve means for controlling the flow of said gas into said firstchamber; a movable seat associated with'said valve means, said seatbeing positioned in response to the pressure of said breathable gas;

inhalation conduit means for conducting breathable gas from said firstchamber to a point of use; a second chamber in said regulator;exhalation conduit means for 0011- v ducting exhalation products fromsaid point of use to said second chamber; a movable wall having one sideexposed to the pressure in said second chamber, the other side of saidwall being exposed to the pressure of the surrounding fluid medium; acheck valve for controlling fluid flow from said second chamber; andmeans operably interconnecting said movable wall and said valve means,whereby, upon inhalation, a reduction in pressure is created in saidexhalation conduit means and in said second chamber thereby to move saidmovable Wall and open said valve means to permit a flow of breathablegas into said first chamber and into said inhalation conduit means.

8. In a breathable gas regulating device: a regulator; a first chamberin said regulator for receiving a breathable gas from a source; valvemeans for controlling the flow of said gas into said first chamber; amovable seat associated with said valve means; spring means normallyurging said seat away from said valve means; means to oppose the forceof said spring means in response to the,

pressure of said breathable gas; inhalation conduit meansfor conductingbreathable gas from said first chamber to a point of use; a secondchamber in said regulator; exhalation conduit means for conductingexhalation products from said point of use to said second chamber; amovable wall having one side exposed to the pressure in said secondchamber, the other side of said wall being exposed to the pressure ofthe surrounding fluid medium; a check valve for controlling fluid flowfrom said second chamber; and means operably interconnecting saidmovable wall and said valve means, whereby, upon inhalation, a reductionin pressure is created in said exhalation conduit means and in saidsecond chamber thereby to move said movable Wall and open said valvemeans to permit a flow of breathable gas into said first chamber andinto said inhalation conduit means.

94 A breathable gas} regulating, device: comprising; in combination:aregulator body; a first-chamber in; said." body; p as'sage means forconducting'a compressedbreathable gas from a source to said firstchamber; a. valve memberinsaid passage means; --a-movableelementiassociated with said valvemember; said element having avalveseat adapted for operableassociation; with said? valve member;fi'rst' springmeans normally urging said" valve membertowardsaid valveseat; a pressure differential area formed onsaid element, saidfareabeing subjeotedto the pressure of said: breathable gas fromsaid source;thereby to urgesaid elementand saidvalve seat toward saidvalve member;second spring means acting on said element in-a direction to opposetheforce of said breathable-gas on said pressure differential area; aninhalation' conduitforconducting said=breathable gas from saidf-firstchamber to a point'of' use; a second chamber formedin-saidbody;an-exhalationconduit for conducting exhalation, products from said pointof use to said secondcham'ber; a diaphragm formingone wall of saidsecond-chamber, said diaphragm havingone side exposed to thepressureinsaid second chamber and'the other side exposed to the pressure ofthesurrounding fluid medium; a check valve for controlling fluid flow fromsaid second chamber; and means operable by movement of said;diaphragminresponse to an inhalation, produced reduction in pressure in saidexhalation conduit'and in said; second chamber to liftsaid valvemember-fromsaid valve seat thereby to permit a fiow ofbreathablegasintosaid'fi'rst, chamber and'into. said inhalation conduit.

10 A breathable gas regulating device comprising, in combination: a.regulator body; a first chamber in said body; a ,source of compressed;breathable gas; ,passage; means-for conductingsaid breathable gasfromsaidsource. to saidfirst' chamb'en a valve member in saidpassage means;a movable element associated, with, said. valve member, said elementhaving a valve seat adapted for.

operable association with said valve member; ,fi'rstsp ring meansnormally urging said valve; member toward saidvalve seat; apressuredifferentialiarea formed; o n said', element, said area being subjected.to the pressureofi said breathable-gas from said source, thereby; tourge saidf element ands'aid valve seat toward said valvemember; secondspring means acting on said' element; inb a, direction to oppose theforce of,said breathable gas on said, pressure differential, area; aninhalation conduit for c.0n: ducting said breathable gas fromsaid'fi'rst chamber to, a. point of use; a second chamber formed in saidbody, said: valve member extending into s'aidfsecondj chamber; an.

exhalation conduit for, conducting exhalation, products.

from saidpoint of use to saidsecond chamber; a di'al-yphragm formingone. wall of saidjsecondjchamber, ,said diaphragm having one side,exposed to thepressure, in said second 'chamb'erand the other sideexposed'to the pressureof the surrounding fluidmedium; a check valve,

for controlling fluid flow from said'second chamber; and lever meansoperable by movementof said diaphragmhin; response to an inhalationproduced, reduction in pressure, in said'exhalation conduit and in said;second chamber. to lift-said; valve member from said'valve seat,thereby to permita flow ofbreathable gas into said first chamber andinto said; inhalation conduit.

11; A breathable gasregulating device comprising, i11

combination: aregulator body; a firstehamberuin; said;

body; a source of, compressed breathable, gas; .passage means forconductingsaid breathable gasfrom said'source to ,said' first chamber; avvalve member in said passage means; a movable element associatedwitlisaid VBIVBJIIGIII: ber, said element havingavalveseatadaptedforoperable, association with jsaid1valve member; firstspring-means normally urging said valve member toward said yalveseatg, apressure differential area.formed'onsaidelernent, said, areabeingsubjected to the pressure of said breathablergas fromsaid'source,thereby to urge said=element andgsaid; valve seat toward said valvemember; second'spring means acting on said"element in a direction tooppose theforce of saidjbreathable gas on said. pressure differentialarea,

aniinhalationconduirfor conducting said breathable gas fronrsaid-fi'rstchamber to a point of1use; a second chambet formed'in' said body, saidvalve member extending into-saidsecondcharnber; an exhalation conduitfor conductingexhaiation products from said .point of use to said,second chamber; a diaphragm forming one wallof said second chamber,said' diaphragm having one side exposed to the pressure in saidsecondchamber and, the other. side exposedito the pressure ofthe surroundingfiuid'medium; a check valve for controlling fluidfiow from saidsecondjchamber, said check valve being carried by saiddiaphrag m; and lever.means operable by, movement of'said' diaphragm in response to aninhalationproduced reduc:

to said'first chamber; a valve; member, in said passage,

means; amovable}element associatedwith said valve member, saidfelernenthaving a valve seat adapted, for operable association with said valvemember; first spring means.- normally urging. said, valve member towardsaid valve, se'atganressurc, differential areat ormed on saidzelement,said'area being subjected to..the.p ress.ur.e,olisaid breathable:gasfromsaid source, thereby-to urge said ,elementand said; valveseattoward said valvemember; secondspringmeans, actingon -.saidlelement, in; a ,direction to oppose the .force.

of said breathable gas on said pressure differential arezu,

an. inhalation, conduit for; conducting said breathable. gas fromsaidfirst chamber. toapoint of vuse; a second champ ber, formed in saidbody,said valve member extending .intov said, second chambergan exhalationconduit for, conduct:- ingpxhalation productsfromsaid point of.usetosaidsec:- ond.chamb er; a diaphragmtorming one. wall; ofsaidondLcharnber, saidldiaphragm having one side exposedto,thepressureinsaid-second chamber and the other side exposedto thepressureof the surroundinglfluid medium; a, check valve, for controllingfluid flow fromsaid second, chamber; lever'meansi operable byrmovementof said die-- phragmiinresponse, to an inhalation prcduced;reduction. inpressure,insaidexhalation conduit andin said'second chamber to liftsaidvalvemember from said valveseat, thereby to permitaflowofubrcathable gas into said first. chamber. and into said inhalationconduit; and means positionedzbetween said valve. member and said sourceof breathable gas, to interrupt the flow of'said gas whenthegasnpressureof said source is reducedto a predetermined level;

13. A breathable,gasregulating device comprising, in combination; a;regulator body; a first chamber, in said body; a source, of compressed,breathable gas; passage means for conductingsaid breathable gasfrornsaid source to said first chamber; a valve member in said passagemeans; a. movable, element' associated, withsaid valve member, saidelementhaving; a. valveseat adapted for operableassociation ,withsaidvalve member; ,first spring, meansnormally urging said valve, member,toward gsaid. valve seat; .a pressure, differential areaformed onsaidelement, .said .area being subjected tothe pressure, of said:breathable; gas from said ysource, thereby to urge said ,elementand-said valve-seattowardtsaid valve member; second spring;means actingonsaid element in a directiomtm oppose the force of, said, breathable,gas on said pressure, differential. area; an inhalation conduitforconductingz saidv breathablehgas from saidlfirst. chamber to apointyof use; a;,second chamber, formed in-said body,v saidrvalye;member extending into'saidsecondchamber; .an exhala:-- tion ,conduitforconduetingexhalation. roductsfrom said point of use to said secondchamber; a diaphragm forming one wall of said second chamber, saiddiaphragm having one side exposed to the pressure in said second chamberand the other side exposed to he pressure of the surrounding fluidmedium; a check valve for controlling fluid flow from said secondchamber; and lever means operable by movement of said diaphragm inresponse to an inhalation produced reduction in pressure in saidexhalation conduit and in said second chamber to lift said valve memberfrom said valve seat thereby to permit a flow of breathable gas intosaid first chamber and into said inhalation conduit; means positionedbetween said valve member and said source of breathable gas to interruptthe flow of said gas when the gas pressure of said source is reduced toapredetermined level; and manually operable means to override saidinterrupting means.

14. A breathable gas regulating device comprising, in combination: aunitary regulator body; a source of compressed breathable gas; abreathable gas receiving chamber formed in said body; a flow restrictingpassage intermediate said source of breathable gas and said chamber; aninhalation conduit for conducting said breathable gas from saidreceiving chamber to a point of use such as the respiration system of anindividual; a valve member positioned in said breathable gas receivingchamber and adapted normally to occlude one end of said passage; amovable element associated with said valve member, said element having avalve seat adapted for operable association with said valve member;first spring means normally urging said valve member toward said valveseat; a pressure diflerential area formed on said element, said areabeing subjected to the pressure of said breathable gas from said source,thereby to urge said element and said valve seat toward said valvemember; second spring means acting on said element in a direction tooppose the force of said breathable gas on said pressure difierentialarea; an exhalation products receiving chamber formed in said valve bodyadjacent said breathable gas receiving chamber; a partition separatingsaid chambers, said valve member extending from said breathable gasreceiving chamber through said partition and having a portion disposedin said exhalation products receiving chamber; an

' exhalation conduit extending between said point of use to saidexhalation products receiving chamber; a flexible diaphragm forming onewall of said exhalation products chamber, said diaphragm having one sideexposed to the fiuid pressure within said exhalation products receivingchamber and the other side exposed to the pressure of the surroundingfluid medium; a bushing positioned in substantially the central area ofsaid diaphragm; fluid flow passages formed in said bushing, thereby toprovide communication between said exhalation products chamher and anambient medium; a flexible disc check valve associated with and adaptednormally to occlude said passages in said bushing, thereby permittingfluid flow only outwardly from said exhalation products chamber; anannular ring extending from said partition intermediate said chamber,said ring being spaced radially from said valve member; an enlarged headon said valve member; a plurality of levers extending over said annularring and beneath said enlarged head, said levers being adapted to engageand be depressed by said diaphragm upon movement thereof inwardly towardsaid exhalation products chamber, said inward movement of said diaphragmbeing caused by an inhalation produced reduction in pressure in saidexhalation conduit and in said exhalation products chamber, thereby tolift said valve member from said seat to permit the flow of breathablegas from said source to said breathable gas receiving chamber andthrough said inhalation conduit to said point of use; a

an inhalation conduit for conducting said breathable gas from saidreceiving chamber to a point of use such as the respiration system of anindividual; a valve member positioned in said breathable gas receivingchamber and adapted normally to occlude one end of said passage; amovable element associated with said valve member, said elementhaving avalve seat adapted for operable associ ation with said valve member;first spring means normally urging said valve member toward said valveseat; a pressure differential area formed on said element, said areabeing subjected to the pressure of said breathable gas from said source,thereby to urge said element and said valve seat toward said valvemember; means to limit movement of said element due to the force of saidbreathable gas; second spring means acting on said element in adirection to oppose the force of said breathable gas on said pressuredifferential area; an exhalation products receiving chamberformed insaid valve body adjacent said breathable gas receiving chamber; apartition separating said chambers, said valve member extending from,

said breathable gas receiving chamber through said partition and havinga portion disposed in said exhalation products receiving chamber; anexhalation conduit extending between said point of use to saidexhalation products receiving chamber; a flexible diaphragm forming onewall of said exhalation products chamber, said diaphragm having one sideexposed to the fluid pressure within said exhalation products chamberand the other side exposed tothe pressure of the surrounding atmostphere; a bushing positioned in substantially the central area of saiddiaphragm; fluid flow passages formed in said bushing, thereby toprovide communication between said exhalation products chamber andambientatmosphere; a flexible disc; check valve associated with andadapted normally to occlude said passages in said bushing, therebypermitting fluid flow only outwardly from said exhalation productschamber; an annular flange surrounding the periphery of said flexiblecheck valve to prevent inadvertent lifting of said flexible check valvefrom said fluid flow passages by surging of ambient atmosphere; anannular ring extending from said partition intermediate said chambers;said ring being spaced radially from said valve member; an enlarged headon said valve member; a plurality of levers extending over said annularring and beneath said enlarged head, said lever being adapted to engageand be depressed by said diaphragm upon movement thereof inwardly towardsaid exhalation products chamber, said inward movement of said diaphragmbeing caused by an inhalation produced reduction in pressure in saidexhalation conduit and in said exhalation products chamber,v thereby tolift said valve member from said seat to permit the flow of breathablegas from said source to said breathable gas receiving chamber andthrough said inhalation'conduit to said point of use; a spring loadedclosure member positioned in said restricted passage between said sourceof breathable gas and said valve member, said closure member beingadapted to be opened by an inhalation created pressure differentialthereacr'oss, said closure member being adapted to shut off the flow ofbreathable gas from said source when the pressure of said breathable gasfrom said source is reduced to a predetermined level; and means tomanually reduce the spring force acting to maintain said closure memberin its shut off position.

16. A breathable gas regulating device comprising, in combination: aunitary regulator body; a source of corn- 15 Pres edhr athable g ssabreath ble gastreceiv ng 1 11 er. tormed in said. body; a w r stri tngrass ge intermediate said source of breathable, gas. and said Chamber;n i h la i n. d tfe conduct ng. aid bre th b a from sai r cei ingvchambe t a po nt f. seuch. as-

th resp i n sy t m of. ndividual; v lve. member Pos tione in. aidjreceiving h mbe and; ada ted, noral to o clu n en of. aid, p ss ge; amovable. leent associa e w t said. valv mem er. n sl dably spos d n aidreg l tor. o. y, sa d ele n i g a valve seat adapted for operableassociation with said valve member; firs pring means normal y urging,said. v l e member toward said. valve. sea anressu e ifferentiial rea.fo m d on said lement, sai ar a b i g ubi eted o he pr s ure ofhreahahle ga f om.s.aid sour.e there y rge. ai l ment..anc1; aid;val. e set. to ar d alv memb r; means. carried y ai e elnenttor lim tingmovement. he of. du to. a d. pressure ofqsaidj breatha le gas; n ta ingme ns cting o aidl la ment in a direction to oppose, the force of saidbreathable ga n id P s re. dilfteren ial r an. xhalat ontprqdv e ei g hmb r. f rmed in ai val b'ody cilia: c nt said reatha gas r eiving chamer; par i on. separating. sa d h.amh .rs,.. id lv m mb r. extending fromsaid brea hable ga -r ce g. chamber thlr ghl a exha lapartition andhaving a portiondijsposedinsai P ducts receivi g, c a ber; an xh la ion.condui ex ndi g. b w en. ai p in of e o-sa djexha l t o productsreceiving. chamber; a flexible diaphragm forming one wall of said,exhalation products chamber, said diaphragm having one side exposed tothe fluidpressure. within said exhalation products. chamber and theother side exposed to the pressure of the surrounding fluid medium; abushing positioned in substantially the central area of said diaphragm;fluid fl'ow passages formed in said bushing thereby to providecommunication between said exhalation products chamber and thesurrounding fluid medium; a flexible disc checkvalve, associated withand adapted normally to occlude. said passages in said"bushin-g, therebypermitting fluidflow only outwardly from said exhalation productschamher; an; annular flange surrounding the periphery ofjsaid flexiblecheck valve to prevent inadvertent lifting ofsaid flexible, check valvefrom said fluid flow passages, by surging of said fluid medium; anannular ring extending from said partition intermediate said chambers,said ring being spaced radially from said valve; an enlarged" head onsaid valve member; a plurality of levers extending over said annularring and beneath said enlargedhead, said lever being adapted to engageand be depressed by said diaphragm upon movement thereof inwardly towardsaidexhalation products chamber, said inward movement of said; diaphragmbeing caused by an inhalation produced reduction in pressure in said"exhalation conduit andin said exhalation products cham- 1 ber, therebyto lift said valve member from said seat to. permit the flow ofbreathable gas from said source to said breathable gas receiving chamberand through said" inhalation conduit to said point ofv use; a springloaded" closure member positioned in said restricted passage be tweensaid source of'breathablje gas and said valve member, said closuremember being adapted to be opened'by an inhalation created pressureditferential thereacross, said closure member being adapted to shut offthe flow of breathable gas from said" source when the source. pressureof said breathable, gas is reduced to a predetermined level; and meansto manually reduce. the spring force acting to maintain said closuremember in its shut off positron.

17. A breathable gas regulating device comprising; first passage meansfor conducting a breathable gas from a source to a point of use; achamber in said device; second passage means for conducting expired'gasfrom said point of use to saidchamber; a movable wall forming one sideof said" chamber, said movable wall being subjected on one side to. thepressure in said chamber and on the other side to the pressure of thesurrounding fluid. medium; valve means for controllingthe. flow ofbreathable gas through said first passage means;means operablyassociatedwith said movable wall for opening said valve meansupon a reductionv ofthe. pressure in. said second passage means and in said chamber therebyto permit, flew of said breathable gas through said first passage means;and gas reserve valve means positioned, upstream from said, valve meansfor interrupting the flow of said breathable, gas when the sourcepressure thereof i'sreduced to a predetermined level.,

18: A breathable, gas regulating device comprising; a. source ofbreathable gas; a first passage for conducting breathable gas from saidsource to a point.offuse;.an

whereby to open said, valve upon an inhalation produced reduction inpressure, on said other side of said dia.-- phragm; and gas reservevalve means disposed in said, first'passage. to limitfl'ow of saidbreathable gas to said. firstpassage when a predetermined low pressurelimit of' gas from said, source is reached.

'19; A breathable gas regulator comprising; a body formed for connectionwith. a source ofcompressed gas and? with conduitsleading to and from apoint of'use; a diaphragm: secured to saidbody for movement in responseto, pressure differences on opposite sides thereof, 'said' diaphragmhaving a firstv side exposed to ambient fluid and a second side exposedto the pressure at the point ofv use offthe'gas; valve means in saidregulator for controlling-the'flow of gas from said source into saidregulator; lever means transmitting motion from said diaphragm to aportion of said valve means, movement of said diaphragm-in'response topressure reductions on saidsecond side serving-to move said valve meansin an opening direction; signal means in said body operative when thegas in saidsource approaches depletion to resist move:- ment of aportion of said valve means in anopeningdirection; and manually operablemeans insaid body' for" diaphragm; saiddiaphragm being exposed on oneside to thepressure of the; surrounding fluid medium; the other side-ofsaiddiaphragm being exposed to-. pressure of thegas delivered tothepointof use; an exhalation valve having a discharge opening to-said' fluidmedium; secondpassage means extending from-said point of use-to saidexhalationvalve; means operatively connecting said dia phragm: and saidinlet valve to open the latterupon an inhalationtproduced reductioninpressure -upon said other sideof said diaphragmgas reserve valvemeansdisposed in said first passage; means resiliently urging saidreserve valve' meanstoward a closedi positionto resist'the flow ofbreathable gas through saidfirst passage; and selectively operated meansfor rendering said urging means inoperative and relieving suchresistance to breathable gas flow.

2'1; A breathable gas regulating device comprising; a-

source of breathablegas; means forming a first passage for conductingbreathable gas from saidsource to a point' ofuse; means formingafloating valveseat in said'passage, forming means, said valve seathaving a. bore constir tuting part ofsaid' fi'rst passage; an inletvalve in said first passage, said inlet valve having an extension ofpredetermined cross-sectional area and length to enter and close thebore in said floating valve seat prior to engagement of the valve Withsaid seat; means resiliently urging said inlet valve toward a closedposition; a respiration responsive diaphragm, said diaphragm beingexposed on a first side to the pressure of the surrounding fluid mediumand on the second side to the pressure of the gas at the point of use;an exhalation valve having a discharge opening to said surrounding fluidmedium; second passage means leading from said point of use to saidexhalation valve; means operatively connecting said diaphragm and saidinlet valve to open the latter upon an inhalation produced reduction inpressure upon said second side of said diaphragm; and means for applyingbreathable gas from said source to said floating valve seat formingmeans 5 variations in gas source pressure.

References Cited in the file of this patent UNITED STATES PATENTS 102,269,904 Erickson Jan. 13, 1942 2,552,595 Seeler May 15, 1951 2,695,609Nourse Nov. 30, 1954 FOREIGN PATENTS 503,950 Belgium Oct. 10, 1952663,202 Great Britain Dec. 19, 1951

